Manufacturing method of semiconductor device comprising oxide semiconductor

Abstract

A semiconductor device for high power application in which a novel semiconductor material having high mass productivity is provided. An oxide semiconductor film is formed, and then, first heat treatment is performed on the exposed oxide semiconductor film in order to reduce impurities such as moisture or hydrogen in the oxide semiconductor film. Next, in order to further reduce impurities such as moisture or hydrogen in the oxide semiconductor film, oxygen is added to the oxide semiconductor film by an ion implantation method, an ion doping method, or the like, and after that, second heat treatment is performed on the exposed oxide semiconductor film.

What is claimed is: 
     
       1. A method for manufacturing a semiconductor device, comprising the steps of:
 forming an oxide semiconductor layer comprising indium; 
 performing a first heat treatment on the oxide semiconductor layer; 
 adding oxygen into the oxide semiconductor layer; and 
 performing a second heat treatment on the oxide semiconductor layer after adding oxygen, 
 wherein at least a top surface of the oxide semiconductor layer comprises a crystal region. 
 
     
     
       2. The method for manufacturing a semiconductor device according to  claim 1 , wherein the crystal region comprises a crystal with a size greater than or equal to 1 nm and less than or equal to 20 nm. 
     
     
       3. The method for manufacturing a semiconductor device according to  claim 1 , wherein c-axes of the crystal region are aligned in a direction which is substantially perpendicular to the top surface of the oxide semiconductor layer. 
     
     
       4. The method for manufacturing a semiconductor device according to  claim 1 , wherein the oxide semiconductor layer has a composition in which a Zn content is larger than an In or Ga content in atomic %. 
     
     
       5. The method for manufacturing a semiconductor device according to  claim 1 , wherein the step of adding oxygen is performed by introducing oxygen ions. 
     
     
       6. The method for manufacturing a semiconductor device according to  claim 1 , wherein the first heat treatment is performed in an atmosphere comprising an inert gas. 
     
     
       7. The method for manufacturing a semiconductor device according to  claim 1 , wherein the second heat treatment is performed in an atmosphere comprising oxygen. 
     
     
       8. The method for manufacturing a semiconductor device according to  claim 1 , wherein the oxide semiconductor layer further comprises gallium and zinc. 
     
     
       9. The method for manufacturing a semiconductor device according to  claim 1 , wherein the oxide semiconductor layer further comprises zinc and a metal other than indium and zinc. 
     
     
       10. The method for manufacturing a semiconductor device according to  claim 1 , wherein temperatures of the first heat treatment and the second heat treatment are higher than or equal to 500° C. and lower than or equal to 850° C. 
     
     
       11. The method for manufacturing a semiconductor device according to  claim 1 , further comprising the step of:
 processing the oxide semiconductor layer by etching to form an island-shaped oxide semiconductor layer before the first heat treatment. 
 
     
     
       12. The method for manufacturing a semiconductor device according to  claim 1 , further comprising the steps of:
 forming a gate insulating layer over the oxide semiconductor layer; and 
 forming a gate electrode over the gate insulating layer. 
 
     
     
       13. A method for manufacturing a semiconductor device, comprising the steps of:
 forming a gate electrode; 
 forming a gate insulating layer over the gate electrode; 
 forming an oxide semiconductor layer comprising indium over the gate insulating layer; 
 performing a first heat treatment on the oxide semiconductor layer; 
 adding oxygen into the oxide semiconductor layer; and 
 performing a second heat treatment on the oxide semiconductor layer after adding oxygen, 
 wherein at least a top surface of the oxide semiconductor layer comprises a crystal region. 
 
     
     
       14. The method for manufacturing a semiconductor device according to  claim 13 , wherein the crystal region comprises a crystal with a size greater than or equal to 1 nm and less than or equal to 20 nm. 
     
     
       15. The method for manufacturing a semiconductor device according to  claim 13 , wherein c-axes of the crystal region are aligned in a direction which is substantially perpendicular to the top surface of the oxide semiconductor layer. 
     
     
       16. The method for manufacturing a semiconductor device according to  claim 13 , wherein the oxide semiconductor layer has a composition in which a Zn content is larger than an In or Ga content in atomic %. 
     
     
       17. The method for manufacturing a semiconductor device according to  claim 13 , wherein the step of adding oxygen is performed by introducing oxygen ions. 
     
     
       18. The method for manufacturing a semiconductor device according to  claim 13 , wherein the first heat treatment is performed in an atmosphere comprising an inert gas. 
     
     
       19. The method for manufacturing a semiconductor device according to  claim 13 , wherein the second heat treatment is performed in an atmosphere comprising oxygen. 
     
     
       20. The method for manufacturing a semiconductor device according to  claim 13 , wherein the oxide semiconductor layer further comprises gallium and zinc. 
     
     
       21. The method for manufacturing a semiconductor device according to  claim 13 , wherein the oxide semiconductor layer further comprises zinc and a metal other than indium and zinc. 
     
     
       22. The method for manufacturing a semiconductor device according to  claim 13 , wherein temperatures of the first heat treatment and the second heat treatment are higher than or equal to 500° C. and lower than or equal to 850° C. 
     
     
       23. The method for manufacturing a semiconductor device according to  claim 13 , further comprising the step of:
 processing the oxide semiconductor layer by etching to form an island-shaped oxide semiconductor layer before the first heat treatment. 
 
     
     
       24. A method for manufacturing a semiconductor device, comprising the steps of:
 forming an oxide semiconductor layer comprising indium; 
 adding oxygen into the oxide semiconductor layer by an ion implantation method or an ion doping method; and 
 performing a heat treatment on the oxide semiconductor layer after adding oxygen, 
 wherein at least a top surface of the oxide semiconductor layer comprises a crystal region. 
 
     
     
       25. The method for manufacturing a semiconductor device according to  claim 24 , wherein the crystal region comprises a crystal with a size greater than or equal to 1 nm and less than or equal to 20 nm. 
     
     
       26. The method for manufacturing a semiconductor device according to  claim 24 , wherein c-axes of the crystal region are aligned in a direction which is substantially perpendicular to the top surface of the oxide semiconductor layer. 
     
     
       27. The method for manufacturing a semiconductor device according to  claim 24 , wherein the heat treatment is performed in an atmosphere comprising oxygen. 
     
     
       28. The method for manufacturing a semiconductor device according to  claim 24 , further comprising the step of:
 processing the oxide semiconductor layer by etching to form an island-shaped oxide semiconductor layer before adding oxygen. 
 
     
     
       29. The method for manufacturing a semiconductor device according to  claim 24 , wherein the heat treatment is performed in a state in which the top surface of the oxide semiconductor layer is exposed. 
     
     
       30. The method for manufacturing a semiconductor device according to  claim 24 , wherein the step of adding oxygen is performed by producing plasma of oxygen gas, mass-separating ion species and accelerating the mass-separated ion species. 
     
     
       31. The method for manufacturing a semiconductor device according to  claim 24 , further comprising the steps of:
 forming a gate electrode; and 
 forming a gate insulating layer over the gate electrode, 
 wherein the oxide semiconductor layer is formed over the gate insulating layer. 
 
     
     
       32. A method for manufacturing a semiconductor device, comprising the steps of:
 forming an oxide semiconductor layer comprising indium; 
 adding oxygen into the oxide semiconductor layer by an ion implantation method or an ion doping method; and 
 performing a heat treatment on the oxide semiconductor layer after adding oxygen; 
 forming a gate insulating layer over the oxide semiconductor layer; and 
 forming a gate electrode over the gate insulating layer, 
 wherein at least a top surface of the oxide semiconductor layer comprises a crystal region. 
 
     
     
       33. The method for manufacturing a semiconductor device according to  claim 32 , wherein the crystal region comprises a crystal with a size greater than or equal to 1 nm and less than or equal to 20 nm. 
     
     
       34. The method for manufacturing a semiconductor device according to  claim 32 , wherein c-axes of the crystal region are aligned in a direction which is substantially perpendicular to the top surface of the oxide semiconductor layer. 
     
     
       35. The method for manufacturing a semiconductor device according to  claim 32 , wherein the heat treatment is performed in an atmosphere comprising oxygen. 
     
     
       36. The method for manufacturing a semiconductor device according to  claim 32 , further comprising the step of:
 processing the oxide semiconductor layer by etching to form an island-shaped oxide semiconductor layer before adding oxygen. 
 
     
     
       37. The method for manufacturing a semiconductor device according to  claim 32 , wherein the heat treatment is performed in a state in which the top surface of the oxide semiconductor layer is exposed. 
     
     
       38. The method for manufacturing a semiconductor device according to  claim 32 , wherein the step of adding oxygen is performed by producing plasma of oxygen gas, mass-separating ion species and accelerating the mass-separated ion species. 
     
     
       39. The method for manufacturing a semiconductor device according to  claim 32 , wherein the gate insulating layer is formed after the heat treatment is performed.